Phishing (also known as 419 scams), where criminals attempt to elicit payments or personal details by e-mail, are now well known, so practitioners are turning to telephone-based variants. The principal method is “vishing” (voice phishing), where the perpetrators call victims posing as their bank and ask them to verify their identities by divulging personal details, often using an automated system. In the most convincing version, the target is not asked for details on the spot, but told to call the bank’s “fraud department” on a specified security number. “Smishing” (SMS phishing) is the latest adaptatation, where initial contact is made by text message.

Jackie Barwell, of First Data, the credit card processing company, says: “The fraudsters tend to say that they want to check that a suspicious transaction on the victim’s account is genuine. Even people who are fairly savvy fall for it.”

She adds that anyone who is contacted by a supposed bank or building society should refuse to answer any questions and instead call the institution on its standard number (printed on the back of credit and debit cards) to check the situation.